stormwater erosion and sedimentation control inspector’s manual

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FLORIDA STORMWATER EROSION AND SEDIMENTATION CONTROL

INSPECTOR’S MANUAL

Florida Department of Environmental Protection

Nonpoint Source Management SectionTallahassee, Florida

July 2008

This publication was funded in part by the Florida Department of Environmental Protectionwith a Section 319 Nonpoint Source Management Program Grant from U.S. Environmental

Protection Agency.


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CONTENTS

LIST OF ACRONYMS AND ABBREVIATIONS ....................................................IX

INTRODUCTION....................................................................................................XI

Purpose and Contents xi

CHAPTER 1: EROSION AND SEDIMENTATION .................................................1

1.1 The Erosion Process 1

1.2 Types of Water Erosion 2

1.3 Factors Influencing Erosion 2

1.4 Impacts of Erosion and Sedimentation 4

1.5 Erosion and Sediment Hazards Associated with Land Development 5

1.6 Principles of Erosion and Sediment Control 6

CHAPTER 2: SOILS ..............................................................................................92.1 Introduction to Soils 9

2.2 Soil Classification and Properties 10

2.3 Soil Surveys 15

CHAPTER 3: REGULATIONS AND STATUTORY REQUIREMENTS ...............17

3.1 Introduction 17

3.2 NPDES Stormwater Permi tting Regulations and Statuto ryRequirements 19

3.3 Construct ion Stormwater Pollution Prevention Plan Template 25

CHAPTER 4: BEST MANAGEMENT PRACTICES FOR EROSION ANDSEDIMENTATION CONTROL....................................................... 33

4.1 Construct ion Sequencing 33

4.2 Pollution Source Controls on Construction Sites 36

4.3 Stabilized Construct ion Exit 39

4.4 Perimeter Contro ls 44

4.5 Storm Drain Inlet Protection 75

4.6 Temporary Sediment Trap 95

CHAPTER 5: BEST MANAGEMENT PRACTICES FOR DEWATERINGOPERATIONS .............................................................................125

5.1 Introduction 125

5.2 Limi tations 127

5.3 Implementation 127

5.4 Inspection and Maintenance 128


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CHAPTER 6: BEST MANAGEMENT PRACTICES FOR STORMWATERMANAGEMENT...........................................................................147


6.2 Earthwork Specifications 149

6.3 Stormwater Retention Basin 1506.4 Exfilt ration Trench 153

6.5 Porous Pavement 163

6.6 Concrete Grid and Modular Pavement 165

6.7 Stormwater Detention Basin 167

6.8 Underdrain and Filtration Systems 171

6.9 Swales 177

6.10 Stormwater Conveyance Channel 182

6.11 Paved Flume 186

6.12 Divers ion 188

6.13 Check Dam 192

6.14 Outlet Protection 194

6.15 Riprap 199

6.16 Grid Confinement System 203

6.17 Cellular Concrete Block 206

6.18 Maintenance 211

CHAPTER 7: BEST MANAGEMENT PRACTICES—VEGETATION FOR

EROSION CONTROL.................................................................. 221


7.2 Surface Roughening 221

7.3 Topsoi ling 227

7.4 Temporary Seeding 229

7.5 Permanent Seeding 231

7.6 Sodding 235

7.7 Mulching 241

7.9 Tree Preservation and Protection 263

7.10 Vegetative Streambank Stabil ization 271

CHAPTER 8: THE EROSION AND SEDIMENT CONTROL PLAN................... 279


8.2 Elements of the Erosion and Sediment Contro l Plan 279

8.3 Implementing the Erosion and Sediment Contro l Plan 281


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CHAPTER 9: INSPECTION AND ENFORCEMENT.......................................... 285


9.2 The Role of the Inspector 285

9.3 Site Inspection 287

9.4 Regulatory Agencies 295

REFERENCES.................................................................................................... 315

LIST OF TABLES

Table 2.1. USDA Particle Size Classes........................................................................11

Table 2.2. USDA Soil Permeability Classes .................................................................13

Table 4.1. Size of Slope Drain ......................................................................................61

Table 4.2. Minimum Top Width (W) and Outlet Height (Ho) Required for

Sediment Trap Embankment According to Height of Embankment(feet) ............................................................................................................96

Table 4.3. Minimum Pipe Diameter for Pipe Outlet Sediment Trap According toMaximum Size of Drainage Area .................................................................97

Table 5.1. Comparison of Dewatering Technologies..................................................126

Table 6.1. Grass Establishment Alternatives..............................................................180

Table 7.1. Organic Mulch Materials and Application Rates ........................................242

Table 7.2. Conditions Where Vegetative Streambank Stabilization Is Acceptable .................................................................................................274

LIST OF FIGURESFigure 2.2. Guide to the Textural Classification of Soils ________________________11

Figure 4.3a. Temporary Gravel Construction Entrance _________________________41

Figure 4.3b. Soil Tracking Prevention Device_________________________________42

Figure 4.3c. Construction Entrance with Wash Rack ___________________________43

Figure 4.4a. Silt Fence __________________________________________________47

Figure 4.4b. Installing a Filter Fabric Silt Fence _______________________________48

Figure 4.4c. Double Row Staked Silt Fence __________________________________50

Figure 4.4d. Proper Placement of a Silt Fence at the Toe of a Slope_______________50

Figure 4.4e. Temporary Diversion Berm_____________________________________55

Figure 4.4f. Temporary Fill Diversion_______________________________________57

Figure 4.4g. Overside Drain ______________________________________________60

Figure 4.4h. Flared End Section Schematic __________________________________61

Figure 4.4i. Flared End Section Specifications _______________________________62

Figure 4.4j. Temporary Slope Drain________________________________________64

Figure 4.4k. Slope Drain_________________________________________________65

Figure 4.4l. Type I and II Floating Turbidity Barriers ___________________________70


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Figure 4.4m. Type III Floating Turbidity Barrier ________________________________71

Figure 4.4n. Typical Installation Layouts_____________________________________72

Figure 4.5a. Silt Fence Drop Inlet Sediment Barrier ____________________________77

Figure 4.5b. Filter Fabric Drop Inlet Sediment Filter____________________________78

Figure 4.5c. Gravel and Wire Mesh Drop Inlet Sediment Filter ___________________80

Figure 4.5d. Block and Gravel Drop Inlet Sediment Filter________________________81

Figure 4.5e. Gravel Filters for Area Inlets____________________________________84

Figure 4.5f. Sod Drop Inlet Sediment Filter __________________________________85

Figure 4.5g. Gravel Curb Inlet Sediment Filter ________________________________87

Figure 4.5h. Gravel Curb Inlet Sediment Filter with Overflow Weir_________________88

Figure 4.5i. Block and Gravel Curb Inlet Sediment Barrier ______________________89

Figure 4.5j. Curb Inlet Gravel Filters _______________________________________90

Figure 4.5k. Curb Inlet Sediment Barrier ____________________________________92

Figure 4.5l. Gravel Bag Curb Sediment Filters _______________________________93

Figure 4.5m. Curb and Gutter Sediment Barrier _______________________________94

Figure 4.6a. Earth Outlet Sediment Trap ____________________________________98

Figure 4.6b. Pipe Outlet Sediment Trap _____________________________________99

Figure 4.6c. Stone Outlet Sediment Trap ___________________________________101

Figure 4.6e. Excavated Drop Inlet Sediment Trap ____________________________102

Figure 4.6f. Storm Inlet Sediment Trap ____________________________________103

Figure 4.6g. Small Sediment Trap Located in a Stormwater ConveyanceChannel __________________________________________________104

Figure 4.6h. Sediment Containment Filter Bag_______________________________105

Figure 4.7a. Sediment Basin Storage Volumes ______________________________107

Figure 4.7b. Sample Plan View of Baffle Locations in Sediment Basins ___________108

Figure 4.7c. Sediment Basin Schematic Elevations ___________________________110

Figure 4.7d. Antivortex Device Design _____________________________________112

Figure 4.7e. Riser Pipe Conditions ________________________________________113

Figure 4.7f. Location of Anti-seep Collars __________________________________114

Figure 4.7g. Emergency Spillway _________________________________________114

Figure 4.7h. Sediment Basin_____________________________________________115

Figure 4.8a. Rock Check Dam ___________________________________________121

Figure 4.8b. Rock Check Dam Details _____________________________________122

Figure 5.4. Dewatering Operations Flow Chart______________________________129

Figure 6.3a. Off-Line Treatment Systems___________________________________151Figure 6.3b. Schematic of Flow Characteristics Associated with Infiltration from

Retention Ponds during Low and High Water Table Conditions________ 152

Figure 6.4a. Cross-Section of Typical Infiltration/Exfiltration System for Parkingor Roads __________________________________________________154

Figure 6.4b. Sample Application of a Vegetated Area for Pretreatment of RunoffPrior to Exfiltration in Frederick County, Maryland __________________155


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Figure 6.4c. Examples of Typical Underground Percolation Systems forRetrofitting Existing Storm Sewer Systems in Orlando, Florida ________159

Figure 6.4d. Detailed Schematic of a Typical Observation Well__________________161

Figure 6.5. Examples of Porous Pavement Drainage Systems _________________164

Figure 6.6. Types of Grid and Modular Pavement ___________________________166

Figure 6.7a. Typical Detention Basin Hydrographs ___________________________168Figure 6.7b. Examples of Dead Storage Areas in Wet Ponds ___________________169

Figure 6.7c. Wet Detention System, Pond Configuration – A____________________170

Figure 6.7d. Wet Detention System, Pond Configuration – B____________________170

Figure 6.8a. Cross-Section of Stormwater Discharge Structure with "MixedMedia" Bank Filter System ____________________________________172

Figure 6.8b. Illustration of Typical "Natural Soil" Bank Filtration System with BoxInlet Drop Spillway and "V" Notched Weir (Wet Detention Facility) _____173

Figure 6.8c. Typical Subdivision Layout Showing On-Line Detention Pond andOutfall ____________________________________________________ 174

Figure 6.8d. Typical Subdivision Layout Showing Off-Line Detention Pond andOutfall ____________________________________________________175

Figure 6.8e. Typical Cross-Section of Elevated Sand Filter for StormwaterTreatment Used in Conjunction with Dry Detention Facility ___________176

Figure 6.9a. Typical Swale Block Cross-Section _____________________________178

Figure 6.9b. Typical Waterway Shapes and Mathematical Expressions forCalculating Cross-Sectional Area, Top Width, and Hydraulic Radius____179

Figure 6.10a. Typical Waterway Cross-Sections ______________________________184

Figure 6.10b. Typical Stone-Lined Waterways ________________________________185

Figure 6.11. Paved Flume_______________________________________________187

Figure 6.12. Types of Diversions _________________________________________190

Figure 6.13. Spacing Between Check Dams ________________________________193

Figure 6.14a. Energy Dissipator ___________________________________________195

Figure 6.14b. Energy Dissipator ___________________________________________196

Figure 6.14c. Pipe Outlet Conditions _______________________________________197

Figure 6.14d. Paved Channel Outlet________________________________________198

Figure 6.15a. Rock-Lined Channel _________________________________________200

Figure 6.15b. Riprap Slope Protection ______________________________________201

Figure 6.15c. Toe Requirements for Bank Stabilization _________________________202

Figure 6.16a. Grid Confinement System_____________________________________203

Figure 6.16b. Vegetative Protection ________________________________________204

Figure 6.16c. Gravity Retaining Wall _______________________________________204

Figure 6.17a. Slope Protection ____________________________________________207

Figure 6.17b. Channel Bottom Protection____________________________________207

Figure 6.17c. Grout Illustration ____________________________________________210

Figure 6.17d. Revegetation_______________________________________________210

Figure 7.2a. Stair-Stepped Slope _________________________________________223


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Figure 7.2b. Grooved or Serrated Slope____________________________________224

Figure 7.2c. Terraced Slope _____________________________________________225

Figure 7.2d. Roughening with Tracked Machinery ____________________________226

Figure 7.6a. Sodding___________________________________________________236

Figure 7.6b. Sodding Swales and Waterways _______________________________238

Figure 7.7a. Typical Orientation of Treatment 1 – Soil Stabilization Blanket ________244

Figure 7.7b. Typical Treatment 1 – Soil Stabilization Blanket Installation Guide _____246

Figure 7.7c. Erosion Blankets and Turf Reinforcement Mats – Slope Installation ____247

Figure 7.7d. Typical Treatment 2 – Soil Stabilization Matting Slope Installation______248

Figure 7.7e. Erosion Blankets and Turf Reinforcement Mats – ChannelInstallation_________________________________________________249

Figure 7.7f. Typical Treatment 2 – Soil Stabilization Matting Installation___________250

Figure 7.7g. Stakes, Staples, and Pins for the Installation of Soil StabilizationMatting ___________________________________________________252

Figure 7.7h. General Staple Pattern Guide and Recommendation for Treatment

2 – Soil Stabilization Matting___________________________________253Figure 7.8a. Benefits of Trees____________________________________________255

Figure 7.8b. Planting Bare Root Seedlings__________________________________256

Figure 7.8c. Planting Balled-and-Burlapped and Container-Grown Trees __________257

Figure 7.8d. Spacing Trees for Safety and Effective Landscaping________________259

Figure 7.9a. Determining the CRZ and TCA_________________________________264

Figure 7.9b. Tree Conservation Area Protection Practices______________________266

Figure 7.9c. Trenching vs. Tunneling ______________________________________268

Figure 7.9d. Proper Pruning Technique ____________________________________270

Figure 7.10a. Typical Annual Curve of Water Levels Correlated with Typical

Vegetative Zones ___________________________________________273Figure 7.10b. Straw Wattles ______________________________________________276


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LIST OF ACRONYMS AND ABBREVIATIONS

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AASHTO American Association of State Highway and Transportation Officials

ANSI American National Standards Institute

ASCE American Society of Civil Engineers

BMP Best management practice

BOD Biochemical oxygen demand

cfs Cubic feet per second

CGPGeneric Permit for Stormwater Discharge fromLarge and Small Construction Activities

CWA Clean Water Act

cm Centimeter

cm2 Square centimeter

CRZ Critical root zone

DBH Diameter breast height

DH&T Department of Highways and Transportation

DOT Department of Transportation

DSWC Division of Soil and Water Conservation

EOS Equivalent opening size

EP Extraction Procedure

EPA U.S. Environmental Protection Agency

ERP Environmental Resource Permit

F.A.C. Florida Administrative Code

FDEP Florida Department of Environmental Protection

FDOT Florida Department of Transportation

F.S. Florida Statutes

ft2 Square foot

ft3 Cubic foot

g Gram

GIS Geographic information system

gpm Gallons per minuteH Height

Ha Hectare

HDPE high-density polyethylene

Ho Outlet height

IECA International Erosion Control Association

IFAS Institute of Food and Agricultural Sciences

LOD Limits of disturbance

kg Kilogram

km Kilometer

km2 Square kilometer

lb Pound

m Meter

m3 Cubic meter

mm MillimeterMS4 Municipal separate storm sewer system

NOEC No observed effects concentration

NOI Notice of Intent

NOT Notice of Termination

NPDES National Pollutant Discharge Elimination System

NRCS Natural Resources Conservation Service

NTU Nephelometric turbidity unit

OSHA Occupational Safety and Health Administration

PAM Polyacrylamide


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PVC Polyvinyl chloride

sec Second

SU Standard unit

SWCC Soil and Water Conservation Commission

SWFWMD Southwest Florida Water Management District

SWPPP Stormwater pollution prevention plan

T Tonne

TCA Tree conservation areaTSS Total suspended solids

UCF University of Central Florida

USACOE U.S. Army Corps of Engineers

USDA U.S. Department of Agriculture

USGS U.S. Geological Survey

USLE Universal Soil Loss Equation

UV Ultraviolet

W Width

WET Whole Effluent Toxicity

yr Year


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INTRODUCTION

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INTRODUCTION

Purpose and Contents

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Purpose and Contents

On average, Florida receives 40 to 60 inches of rain each year from about 130 stormevents. While about 80% of the storms are small, with less than 1 inch of rainfall, thestate also experiences torrential downpours and hurricane rains. These cause runoffcarrying sediment, fertilizers, pesticides, oil, heavy metals, bacteria, and othercontaminants to enter surface waters, causing adverse effects from increased pollutionand sedimentation. The implementation of erosion control measures consistent with

sound agricultural and construction operations is essential to minimizing these impacts.

Florida's stormwater regulatory program requires the use of best management practices(BMPs) during and after construction to minimize erosion and sedimentation and toproperly manage runoff for both stormwater quantity and quality. BMPs are controlpractices that are used for a given set of conditions to achieve satisfactory water qualityand quantity enhancement at a minimal cost. Each BMP has specific application,installation, and maintenance requirements that should be followed to control erosionand sedimentation effectively. Accepted engineering methods must be used in thedesign of these control measures, such as those established by the Florida Departmentof Environmental Protection (FDEP), Florida Department of Transportation (FDOT), U.S.Department of Agriculture’s (USDA) Natural Resources Conservation Service (NRCS),International Erosion Control Association (IECA), American Society of Civil Engineers(ASCE), U.S. Army Corps of Engineers (USACOE), or other recognized organizations.

Insufficient staffing among regulatory agencies, combined with a lack of awarenessamong contractors, historically resulted in a low rate of compliance for implementingthese BMPs. In an effort to address the problem, in 1999 FDEP developed a trainingand certification program on their use, installation, and maintenance. While the programis primarily directed towards inspectors and contractors, permit reviewers and publicworks staff will also benefit. The program’s objectives are as follows:

To ensure that the desired benefits of stormwater management systems arebeing achieved.

To ensure that both the public and private sectors have enough inspectorstrained in the proper installation and maintenance of BMPs during and afterconstruction.

To ensure a consistent level of technical expertise and professional conductfor all individuals responsible for inspecting erosion and sediment controlsand stormwater management systems.


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This updated version of the Florida Stormwater, Erosion, and Sedimentation ControlInspector’s Manual is an important element of FDEP’s training and certification program.It provides a "toolbox" of BMPs with instructions for their use and is designed to be acomprehensive reference source for the conduct of your daily professional duties. Donot attempt to memorize the entire manual. Instead, become familiar enough with it sothat you know where to find information quickly. Review the manual periodically to

improve and maintain your technical and personal skills. Refer to it when facing a newsituation or when in doubt. Try to keep the manual with you while conducting yourduties.

Always remember that the ru les are per formance based—i.e., the measures usedat a construction site must effectively control erosion and prevent sedimentationfrom reaching a regulated receiving water for the site to be in compliance. Theimplementation of BMPs according to this manual is no guarantee of success, noris it a constraint to p revent the use of other more efficient or cost-effectivemeasures.1

Chapters 1 and 2 of the manual provide essential information on the erosion and

sedimentation process, soil classification and properties, and soil surveys. Chapter 3discusses current statutory and regulatory requirements. Chapters 4 through 7 providedetailed information on BMPs for erosion and sedimentation control, dewateringoperations, stormwater management, and vegetation for erosion control. Chapter 8discusses how to develop an erosion and sedimentation control plan, which is theguiding document for describing who and what will control erosion at a specific site, andwhen, where, and how this will be done. Chapter 9 addresses inspection andenforcement issues.

1 Chapter 6 of the Florida Development Manual : A Guide to Sound Land and Water Management contains an extensive

discussion of the use, design, construction, and operation of a wide variety of stormwater management and erosion andsediment control BMPs (available at http://www.dep.state.fl.us/water/nonpoint/docs/nonpoint/erosed_bmp.pdf ).


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CHAPTER 1: EROSION AND SEDIMENTATION

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CHAPTER 1: EROSION ANDSEDIMENTATION

1.1 The Erosion Process 1.2 Types of Water Erosion

1.3 Factors Influencing Erosion- 1.3.1 Soil Characteristics- 1.3.2 Vegetative Cover- 1.3.3 Topography- 1.3.4 Climate (Rainfall)

1.4 Impacts of Erosion and Sedimentation- 1.4.1 Physical Impacts- 1.4.2 Biological Impacts

1.5 Erosion and Sediment Hazards Associated with Land Development

1.6 Princip les of Erosion and Sediment Control

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1.1 The Erosion Process

Soil erosion is the process by which the land surface is worn away by the action ofnatural forces such as wind, water, ice, and gravity. It is caused when sediments aredetached from the soil mass, transported primarily by flowing water or wind, andeventually deposited as sediment. Water erosion is caused when raindrops falling onbare or sparsely vegetated soil detach soil particles. Water flowing over the groundpicks up the particles and carries them. As the runoff gains velocity, it forms channels

and detaches more soil particles. This action cuts rills and gullies into the soil, adding tothe sediment load. Wind erosion is also a significant cause of soil loss, especially inpeninsular Florida. Winds blowing across unvegetated, disturbed land pick up soilparticles and carry them along.2

Sedimentation is the settling out of soil particles transported by water and wind. Itoccurs when the velocity of water in which the particles are suspended is slowed to asufficient degree, and for a sufficient period, to allow the particles to settle out ofsuspension. Heavier particles such as sand and gravel settle out more rapidly than fineparticles such as clay and silt.

Sediment deposition occurs as the velocity of a sediment-transporting stream

decreases. This is particularly important in Florida, where nearly all streams have lowgradients and low velocities. Deposition, rather than transport, is therefore the dominantprocess in most Florida aquatic systems. If the available energy of the water is greaterthan the burden of the sediment load being transported, the moving water erodes the

2 Additional information on wind erosion and i ts control is available from the NRCS (formerly the Soil Conservation

Service) at http://soils.usda.gov/


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soil to obtain additional sediment. If the load is greater than the available energy, someof the transported material is deposited.

Natural or geologic erosion has occurred at a relatively slow rate since the earth wasformed. It is a major factor in creating the earth as we know it today. The great rivervalleys of the Florida Panhandle, the rolling farmlands and orchards of the Central

Ridge, and the productive estuaries and barrier islands of the coast are all products ofgeologic erosion and sedimentation. Except for some cases of shoreline and streamchannel erosion, natural erosion occurs at a very slow and uniform rate, and is a vitalfactor in maintaining environmental balance. Geologic erosion produces about 30% ofall sediment in the United States.

Accelerated eros ion is the increased rate of erosion caused primarily by the removal ofnatural vegetation or alteration of the ground contour. This type of erosion accounts for70% of all sediment generated in this country. Farming and construction are theprincipal causes of accelerated erosion, although any activity that disturbs land canincrease the natural erosion rate.

1.2 Types of Water ErosionThere are two principal types of water erosion: overland erosion and sheet channelerosion. Overland erosion occurs on denuded slopes when raindrops splash and runoff. The largest source of sediment during construction activities, it includes thefollowing:

1 Raindrop erosion or splash erosion results when raindrops dislodge soilparticles and splash them into the air. These dislodged particles are thenvulnerable to sheet erosion.

2. Sheet erosion is caused by shallow sheets of water flowing off the land.These broad, moving sheets of water are seldom the detaching agent, but

the flow transports soil particles detached by raindrops. The shallowsurface flow rarely moves as a uniform sheet for more than a few feetbefore concentrating in low spots on the land surface.

3. Rill erosion develops as the shallow surface flow begins to concentrate inlow spots. The concentrated flow increases in velocity and turbulence,which in turn causes the detachment and transport of more soil particles.This action cuts tiny, well-defined channels called rills, which are usuallyonly a few inches deep.

4. Gully erosion occurs as the flow in rills comes together in larger andlarger channels. The major difference between this and rill erosion is size.

Stream channel erosion occurs as the volume and velocity of flow increase sufficiently tocause the movement of the streambed and bank materials.

1.3 Factors Influencing Erosion

The inherent erosion potential of an area is determined by four principal factors: soilcharacteristics, vegetative cover, topography, and climate (rainfall). Although each ofthese factors is discussed separately, they are inter-related.


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1.3.1 Soil Characteristics

Soil properties that influence erosion by rainfall and runoff consist of those that affect theinfiltration capacity of a soil and those that affect the resistance of the soil to detachmentand transport by flowing or falling water. Four factors are important, as follows:

1. Soil texture (average particle size and gradation).2. Percentage of organic content.

3. Soil structure.

4. Soil permeability.

Soils that contain high percentages of silt and very fine sand are generally the mosterodible. As the clay and organic matter content of these soils increase, their erodibilitydecreases. Clays act as a binder of soil particles and reduce erodibility. However, whileclays have a tendency to resist erosion, once detached from the soil they are easilytransported by water and settle out very slowly.

Organic matter is plant and animal residue in various stages of decomposition. Soilshigh in organic matter have a more stable structure that improves their permeability.They resist raindrop detachment and absorb more rainwater, minimizing erosion. Well-drained and well-graded gravels and gravel-sand mixtures are the least erodible soils.Coarse gravel soils are highly permeable and have a good absorption capacity thateither prevents or delays, and thus reduces, the amount of surface runoff. The study ofsoil characteristics related to soil erodibility is a complex, technical field. Chapter 2provides further information about soils.

The NRCS developed the Universal Soil Loss Equation (USLE) to help simplify theprocess of determining how much soil erosion will occur when using variousconservation practices. However, the accuracy of the USLE in Florida is quite low. It is

also not designed to quantify sediment yields from construction sites.

1.3.2 Vegetative Cover

Vegetative cover plays an extremely important role in controlling erosion:

1. It shields the soil surface from the impact of falling rain.

2. It holds soil particles in place.

3. It maintains the soil's capacity to absorb water.

4. It slows the velocity of runoff.

5. It removes subsurface water through evapotranspiration.

By sequentially scheduling (staging) and limiting the removal of vegetation, and bydecreasing the area and duration of exposure, soil erosion and sedimentation can besignificantly reduced. Special consideration should be given to maintaining vegetativecover on areas of high erosion potential, such as erodible soils, steep or long slopes,stormwater conveyances, and streambanks.


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1.3.3 Topography

The size, shape, and slope of a watershed influence the amount and rate of runoff.Slope length and gradient are key elements in determining the volume and velocity ofrunoff and the erosion risks. As both slope length and gradient increase, the velocityand volume of runoff increase, and the erosion potential is magnified. Slope orientation

can also be a factor in determining erosion potential.

1.3.4 Climate (Rainfall)

The frequency, intensity, and duration of rainfall are fundamental factors in determiningthe amount of runoff. As both the volume and the velocity of runoff increase, thecapacity of runoff to detach and transport soil particles also increases. When storms arefrequent, intense, or of long duration, erosion risks are high. Seasonal changes inrainfall and temperature define the period of the year with the highest risk of erosion.

Land-disturbing activities should be scheduled to take place during periods of lowprecipitation and low runoff. Exposed areas should be stabilized before the period ofhigh erosion risk. Generally, Florida's wet season occurs from May to November, with adry season from November to May. Check with your local water management district orFDOT office for more precise climate information in your area.

1.4 Impacts of Erosion and Sedimentation

Normally, runoff builds up rapidly to a peak and then diminishes. Erosion createsexcessive quantities of sediment, principally during higher flows. During lower flows, asthe velocity of runoff decreases, the transported materials are deposited, only to bepicked up by later peak flows. In this way, sediments are carried downstreamintermittently and progressively from their source. A study of sedimentation fromhighway construction and land development in Virginia indicated that 99% of sedimentdischarge occurred during periods of high flow that took place during only 3% of the

period of measurement (Vice et al., 1969).

Over 4 billion tons (3.6 billion metric tonnes [t]) of sediment are estimated to reach theponds, rivers, and lakes of our country each year, and approximately 1 billion tons(0.9 billion metric tonnes) of this sediment are carried all the way to the ocean.

Approximately 10% of this amount is contributed by erosion from land undergoinghighway construction or land development (SCS, 1980). Although this number mayappear to be small compared with the total, it can represent more than half of thesediment load carried by many streams draining small watersheds undergoingdevelopment.

Sediment yields in streams flowing from established, urbanized drainage basins vary

from approximately 200 to 500 tons per square mile per year (70 to 175 tonnes/squarekilometer/year [t/km2/yr]). In contrast, areas actively undergoing urbanization often havea sediment yield of 1,000 to 100,000 tons per square mile per year (350 to 3,500t/km2/yr) (USGS, 1968). Development is begun on an estimated 4,000 to 5,000 acres(1,620 to 2,025 hectares [ha]) of land throughout the country every day. This includesdevelopment for housing, industrial sites, and highway construction (U.S. CensusBureau, 1987). For very small areas, where construction activities have drasticallyaltered or destroyed vegetative cover and the soil mantle, the sediment derived from 1


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acre of land may be 20,000 to 40,000 times that obtained from adjacent undevelopedfarm or woodland areas.

1.4.1 Physical Impacts

Excessive quantities of sediment result in costly damage to aquatic areas and to private

and public lands. The obstruction of stream channels and navigable rivers by masses ofdeposited sediment reduces hydraulic capacity. This, in turn, causes an increase inflood crests, resulting in flood damage. Sediment fills stormwater conveyances andplugs culverts and stormwater systems, necessitating frequent and costly maintenance.

Municipal and industrial water supply reservoirs lose storage capacity, the usefulness ofrecreational impoundments is impaired or destroyed, navigable channels mustcontinually be dredged, and the cost of filtering muddy water in preparation for domesticor industrial use becomes excessive. The added expense of water purification in theUnited States amounts to millions of dollars each year.

1.4.2 Biological Impacts

The biological effects of sedimentation are even more critical. The presence of fine-grained sediments (clays, silts, and fine sands) in an aquatic system reduces both thekinds and the amounts of organisms present. Sediments alter the aquatic environmentby screening out sunlight and by changing the rate and the amount of heat radiation.This light reduction inhibits photosynthesis, leading to a decline in benthic plant growth.Consequently, the food chain is disrupted, and the population of consumer species isreduced.

The elimination or reduction of benthic organisms decreases the number and variety offood sources for fish, further disrupting the food chain and causing fish to either starve ormove away. A moderate concentration of sediment can impair fish spawning, while ahigh concentration clogs the gills of fish and invertebrates. The result may be that clear

waterbodies that once supported populations of game fish, such as bass and bream,become muddied and inhabited by more tolerant "trash" fish such as carp or suckers.

Coarser-grained materials also blanket bottom areas and suppress aquatic life found onand in these areas. Where currents are sufficiently strong to move the bed load, theabrasive action of these materials accelerates channel scour caused by, or associatedwith, higher flood stages induced by sedimentation.

1.5 Erosion and Sediment Hazards Associated withLand Development

Land development activities affect the natural or geologic erosion process by exposingdisturbed soils to precipitation and to surface stormwater runoff. The shaping of land fordevelopment alters the land cover and the soil in many ways. These alterations oftendetrimentally affect onsite stormwater patterns and, eventually, offsite stream andstreamflow characteristics. Protective vegetation is reduced or removed, earth isexcavated, topography is altered, the removed soil material is stockpiled—often withoutprotective cover—and the physical properties of the soil itself are changed.


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The development process is such that many people may be adversely affected even bya small development project. Uncontrolled erosion and sediment from these areas oftencause considerable economic damage to individuals and to society in general. Thehazards associated with development include the following:

1. A large increase in areas exposed to stormwater and soil erosion.

2. Increased volumes of stormwater, accelerated soil erosion and sedimentyield, and higher peak flows caused by the following:

a. Removal of existing protective vegetative cover.

b. Exposure of underlying soil or geologic formations that are less perviousand/or more erodible than the original soil surface.

c. Reduced capacity of exposed soils to absorb rainfall due to compactioncaused by heavy equipment

d. Enlarged drainage areas caused by grading operations, diversions, andstreet construction.

e. Prolonged exposure of disturbed areas that are left unprotected due to

scheduling problems or delayed construction.

f. Shortened periods of concentrated surface runoff caused by alterations insteepness, distance, and surface roughness, and by the installation of"improved" storm drainage facilities.

g. Increased impervious surfaces such as streets, buildings, sidewalks, andpaved driveways and parking lots.

3. Alteration of the ground water regime that may adversely affect stormwatersystems, slope stability, and the survival of existing or newly establishedvegetation.

4. Creation of exposures facing south and west that may hinder plant growthdue to adverse temperature and moisture conditions.

5. Exposure of subsurface materials that are rocky, acid, droughty, orotherwise unfavorable to the establishment of vegetation.

6. Adverse alteration of surface runoff patterns by construction anddevelopment.

1.6 Principles of Erosion and Sediment Control

For an erosion and sediment control program to be effective, it is imperative thatprovisions for control measures be made in the planning stage. These plannedmeasures, when conscientiously and expeditiously applied during construction, willresult in orderly development without environmental degradation and with cost savings.

The seven principles listed below should be used to the maximum extent possible.Usually, these principles are integrated into a system of vegetative and structuralmeasures, along with management techniques, that are used in developing a plan toprevent erosion and control sediment. In most cases, a combination of limited grading,limited time of exposure, and the judicious selection of erosion control practices andsediment-trapping facilities are the most practical methods of controlling erosion and theassociated production and transport of sediment.


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1. Plan the development to fit the particular topography, soils, drainagepatterns, and natural vegetation of the site.

Detailed planning should be employed to ensure that roadways, buildings, and otherpermanent features of the development conform to the natural characteristics of the site.Large graded areas should be located on the most level portion of the site.

Slope length and gradient are key elements in determining the volume and velocity ofrunoff and its associated erosion. As both slope length and steepness increase, the rateof runoff increases and the potential for erosion is magnified. Where possible, steepvegetated slopes should be left undisturbed. Areas with slope and soils limitationsshould not be used unless sound conservation practices are employed. For instance,where it is necessary to build on long, steep slopes, the practices of benching, terracing,or constructing diversions should be used. Areas subject to flooding should be avoidedor used as part of the stormwater management system. Floodplains should be kept freefrom filling and construction activities since they temporarily store excess runoff, thushelping to avoid erosion and flooding problems downstream.

Erosion control, development, and maintenance costs can be minimized by selecting asite suitable for a specific proposed activity, rather than by attempting to modify a site toconform to that activity. This kind of planning can be more easily accomplished wherethere is a general land use plan based on a comprehensive inventory of soils, water, andother related resources.

2. Minimize the extent of the area exposed at one time and the duration ofexposure.

When land disturbances are required and the natural vegetation is removed, keep thearea and the duration of exposure to a minimum. Plan the stages of development sothat only the areas that are actively being developed are exposed. All other areasshould have a good cover of either temporary or permanent vegetation, or mulch.

Grading should be completed as soon as possible after it has begun. Immediately aftergrading is completed, a permanent vegetative cover should be established. As cutslopes are made and as fill slopes are brought up to grade, these areas also should berevegetated. This is known as staged revegetation. Minimizing the grading of large orcritical areas during the rainy season (the time of maximum erosion potential) reducesthe risk of erosion.

3. Apply perimeter control measures to protect the disturbed area fromoffsi te runoff and to prevent sedimentation damage to areas below thedevelopment si te.

These measures effectively isolate the development site from surrounding properties

and, in particular, control sediment once it is produced, thus preventing its transport fromthe site. Diversions, berms, sediment traps, vegetative filters, and sediment basins areexamples of practices to control sediment. Vegetative and structural sediment controlmeasures are either temporary or permanent, depending on whether they will remain inuse after development is complete. Generally, sediment is retained by (a) filtering runoffas it flows through an area and (b) impounding the sediment-laden runoff for a period sothat the soil particles settle out. The best way to control sediment, however, is to preventerosion, as discussed in the fourth principle.


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4. Apply erosion control measures to prevent excessive onsite damage.

The use of erosion control measures on a site prevents excessive sediment from beingproduced. Keep soil covered as much as possible with temporary or permanentvegetation, or with various mulch materials. Special grading methods, such asroughening a slope on the contour or tracking with a cleated bulldozer, may be used.

Other practices include diversion structures to direct surface runoff from exposed soiland grade stabilization structures to control surface water. These water control devicesmust prevent "gross" erosion in the form of gullies. Lesser types of erosion, such assheet and rill erosion, should be prevented, but often scheduling or the large number ofmeasures required makes this impractical. However, when erosion is not adequatelycontrolled, sediment control is more difficult and expensive.

5. Keep runoff velocities low and retain runoff on the site.

The removal of existing vegetative cover and the resulting increase in impermeablesurface area during development increase both the volume and velocity of runoff. Theseincreases must be taken into account when providing for erosion control. Keeping slopelengths short and gradients low, and preserving natural vegetative cover, can keep

stormwater velocities low and limit erosion hazards.

Runoff from the development site should be safely conveyed to a stable outlet usingstorm drains, diversions, stable waterways, or similar measures. Consideration shouldbe given to installing stormwater detention structures to prevent flooding and damage todownstream facilities resulting from increased runoff from the site. Conveyance systemsshould be designed to withstand the velocities of projected peak discharges. Thesefacilities should be operational as soon as possible after the start of construction.

6. Stabilize disturbed areas immediately after the final grade is attained.

Permanent structures, temporary or permanent vegetation, and mulch, or a combinationof these measures, should be employed as quickly as possible after the land isdisturbed. Temporary vegetation and mulches can be most effective under conditionswhere it is not practical to establish permanent vegetation. Such temporary measuresshould be employed immediately after rough grading is completed if a delay isanticipated in obtaining finished grade. The finished slope of a cut or fill should bestable, and the design should consider ease of maintenance. Stabilize roadways,parking areas, and paved areas with gravel sub-base whenever possible.

7. Implement a thorough maintenance and follow-up program.

This last principle is vital to the success of the six other principles. A site cannot beeffectively controlled without thorough, periodic inspections of the erosion and sedimentcontrol practices. These practices must be maintained, just as construction equipment

must be maintained and materials checked and inventoried. An example of applying thisprinciple is to start a routine "end of day check" to make sure that all control practicesare working properly.


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CHAPTER 2: SOILS

2.1 Introduction to Soils

2.2 Soil Classification and Properties

-2.2.1 Soil Classification

Soil Texture

Soil Hydrologic Group

- 2.2.2 Soil Properties

Erodibility

Slope

Shrink-Swell Potential

Flood Hazard

Soil Reaction (pH)

Wetness

Depth to Bedrock

2.3 Soil Surveys

* * * * * * * * * * * * * * * * * * * *

2.1 Introduction to Soils

To effectively prevent erosion and minimize sedimentation, an understanding of differentsoil types and their properties is essential. Soils form in response to the interaction offive factors: climate, relief, organisms, parent material, and time. Soils form in theparent material, known as the C horizon.3 Marine sands, weathered limestone, and

organic deposits are the common parent materials found in Florida soils.

A soil profile develops as parent material is transformed into soil by soil-formingprocesses. The accumulation of organic matter in O and A horizons, the leaching ofnutrients from A and E horizons, and the translocation and synthesis of clay to form Bhorizons are examples of soil-forming processes that create horizons within a profile. Asoil profile has two or more horizons.

Young soils (A over C horizons) are common in Florida. A soil is said to mature, or age,as the B horizon accumulates clay. Soils with spodic horizons, commonly found inFlorida, are B horizons that have an accumulation of organics, iron, and aluminum fromthe overlying soil. Soil horizons can differ in chemical and physical properties, such as

thickness, texture, color, organic matter, fertility, and pH.

On a volume basis, average topsoil (the A horizon) is 45% minerals, 5% organic matter,and 50% pore space. With depth, organic matter, porosity, and permeability decrease.

3 A horizon consists of a layer of soil parallel to the soil surface whose physical characteristics differ from the layers above

and below it. Each horizon is identified by a capital letter, and the layers within each horizon are identified usinglowercase letters. A is the surface horizon, B is subsoil, and C is the substratum. Most soils comprise the A, B, and Chorizons. E is a subsurface horizon with significant mineral loss. O, the organic horizon, can be either buried or on thesurface. R is hard bedrock.


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Topsoil has the greatest amount of plant andmicrobial activity. It is important as a seedbed, areservoir for nutrients and water, and in the exchangeof gases between the subsoil and atmosphere. Thetopsoil is the horizon most vulnerable to erosion andhuman activities.

Geologic erosion is a natural, ongoing process.Equilibrium between erosion and topsoil formation isestablished for each particular location within a givenarea. The soil loss tolerance (T value) is an estimateof the maximum amount of annual erosion that a soilcan tolerate without a decrease in crop yield. Someof our most fertile regions are floodplain soils thatwere deposited from eroded upland topsoil.However, accelerated erosion due to human activities has detrimental impacts onsiteand downstream. Soil behavior and morphology (structure) change in response to anychange in the five soil-forming factors. In Florida, clay and muck are the two soils

that cause the most problems with turbid ity and erosion.

2.2 Soil Classification and Properties

2.2.1 Soil Classification

Soil engineers and agricultural scientists describe the properties of soils differentlybecause their interests are substantially different. Both soil and civil engineers arefamiliar with the unified and American Association of State Highway and TransportationOfficials (AASHTO) systems, which focus on the engineering properties of soils. Theseclassifications are based on the physical properties of the soil. Initially, soils aredescribed as either coarse- or fine-grained. Coarse-grained soils are further described

by the degree of sorting of particle sizes. Fine-textured soils are further distinguished bytheir liquid and plasticity limits. Particle size analysis is not usually performed.

In contrast, the USDA system of soil classification, used by the agency’s NRCS, focuseson the characteristics of soils that are important for agricultural uses, such as texture,organic matter, and nutrient content. A particle size analysis is necessary before a soilcan be classified using the USDA system. In the USLE, since it was originallydeveloped for use in agricultural areas, the USDA system is used.

Soil Texture

Soil texture depends on the proportions (by weight) of sand, silt, and clay in a soil—oftenreferred to as the particle size distribution. Table 2.1 lists the USDA particle sizeclasses. A triangle is used to categorize soil textures based on their particle size content(see Figure 2.2).

The percentages of sand, silt, and clay in a soil add up to 100. By knowing any twocomponents, one can find the texture name for the soil. For example, a soil with 40%sand and 40% silt is called a loam. A loam also contains 20% clay. A sample with 20%sand and 60% silt is called a silt loam, while one with 60% sand and 30% silt is called asandy loam.


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Table 2.1. USDA Particle Size Classes

Particle Name Size (millimeters [mm])

Gravel > 2.0

Sand 2.0 – 0.1

Very Fine Sand 0.1 – 0.05

Silt 0.05 – 0.002

Clay < 0.002

Figure 2.2. Guide to the Textural Classification of SoilsSource: Erosion and Sediment Control Handbook, Goldman et al., 1988.


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The unified and AASHTO classification systems use a different particle size than theUSDA system to differentiate silt from sand; the former change the classification at0.74 mm, the latter at 0.05 mm. This difference is important because the silt and veryfine sand particles in this size range are most susceptible to erosion and are therefore ofinterest in erosion control planning.

The particle size also is important because the ability of a sediment basin to trap soil isprimarily related to particle size. The smaller the particle, the larger the basin must be tocapture it. Each sediment basin should be designed to capture a certain size particlecalled the design particle. If a soils analysis is to be done on a site, the site plannershould request that the design particle size be specified as a threshold in the analysis(i.e., specify the percent, by weight, of particles larger or smaller than that size).

Sandy soils generally have a higher permeability than fine-textured soils. The amount ofrunoff is lower, and since the particles are relatively large (and thus heavy), they are notcarried far in any runoff that does occur. Sand particles settle out of runoff at the bottomof a slope or in a channel with a gentle slope. Very fine sand particles, however, behavelike silt particles.

Silt is the most important particle size class when soil erodibility is evaluated. The higherthe silt content, the more erodible a soil is. Silt-sized particles are small enough toreduce the permeability of a soil and are also easily carried by runoff. Control measuresshould be designed to prevent the erosion of silt, or at least to contain it onsite.

Clay is the smallest particle size class. A soil with high clay content is quite cohesive— the particles stick together in clumps. Runoff does not pick up clay particles as easily asit does silt. However, once clays are suspended in runoff, they will not settle out untilthey reach a large, calm waterbody. These very small particles have so low a settlingvelocity that they are carried long distances until still water is reached, or until salt watercauses them to clump together again in aggregates.

It is easiest to prevent the erosion of sandy soils. Silts are most susceptible to erosion,but they can be recaptured onsite by applying the control measures described in

control measures must focus on preventing their erosion in the first place.

Although texture is a principal soil characteristic affecting erodibility, three othercharacteristics have a strong influence on erosion potential: organic matter, soilstructure, and permeability.

Organic Matter. Organic matter within a soil is mostly made up of decomposed plantand animal litter. It consists of colloidal particles as small as and smaller than clay

particles. This kind of organic matter helps bind the soil particles together, improves soilstructure, and increases permeability and water-holding capacity. Soils with organicmatter are less susceptible to erosion and more fertile than soils without organic matter.

On a construction site, where extensive grading has removed the original topsoil andexposed layers of earth that have no plant roots growing in them, there is no organicmatter. Such subsoils are likely to be more erodible and less fertile than surface soils.

Chapter 4. Clays are the most difficult to trap once erosion has occurred, and thus


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In another sense of the term, organic matter means plant residue, or other organicmaterial, that is applied to the soil surface. Surface-applied mulch reduces erosion byreducing the impact of raindrops, and by absorbing water and reducing runoff. Itprovides a more hospitable environment for plant establishment, and it eventuallydecomposes and improves the structure and fertility of the soil. Chapter 7 describes theuses of mulch in erosion control.

Soil Structure. Soil structure refers to the arrangement of particles in a soil. In anundisturbed soil with established vegetation, organic matter binds the particles intoclumps called aggregates, producing what is called a granular structure. This isdesirable because permeability and water-holding capacity are increased and theclumped particles are more resistant to erosion.

The grading and compaction of soils during construction destroy their natural structure,reduce permeability, and increase runoff and erodibility. The direct impact of raindropson a soil unprotected by mulch or vegetation also breaks up soil aggregates andincreases erodibility.

Soil Permeabili ty. Soil permeability refers to the ability of the soil to allow air and waterto move through it. Table 2.2 lists the USDA permeability classes. Soil texture,structure, and organic matter all contribute to permeability. Sites with highly permeablesoils absorb more rainfall, produce less runoff, are less susceptible to erosion, andsupport plant growth more successfully.

Graded areas must meet certain standards of compaction to ensure a stable foundationsurface. The infiltration of water into a large fill is not desirable because it may reducethe fill's stability. Compaction increases stability, but by lessening the amount ofinfiltration, soil permeability is reduced and surface runoff and surface erosion increase.When grass is planted on fills and paved diversion ditches are installed mid-slope tocarry away excess runoff, surface erosion is reduced.

Table 2.2. USDA Soil Permeabili ty Classes

Permeabili ty ClassEstimated Inches Per Hour through

Saturated, Undisturbed Coresunder ½-Inch Head of Water

Very Slow < 0.06

Slow 0.06 – 0.2

Moderately Slow 0.2 – 0.6

Moderate 0.6 – 2.0

Moderately Rapid 2.0 – 6.0

Rapid 6.0 – 20

Very Rapid > 20


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Soil Hydrologic Group

The hydrologic soil group is a direct reflection of the infiltration rate of the soil. Thehydrologic soil groups, according to their infiltration and transmission rates, are asfollows:

1. Soils having high infiltration rates even when thoroughly wetted (low runoffpotential);

2. Soils having moderate infiltration rates when thoroughly wetted;

3. Soils having slow infiltration rates when thoroughly wetted; and

4. Soils having very slow infiltration rates when thoroughly wetted (high runoffpotential).

2.2.2 Soil Properties

The properties of soil at a construction site should be identified for planning purposes.

Each soil type has different characteristics, including permeability, infiltration, seasonalwetness, depth to the water table, depth to bedrock, texture, shrink-swell potential,erodibility, and slope. Variations in the properties of soil affect its ability to support heavyloads, to serve as a medium for wastewater or solid waste disposal, to percolaterainwater, to hold its shape and slope after excavation, or to grow vegetation. Thefollowing sections describe important soil characteristics.

Erodibility

The major soil consideration in controlling erosion and sedimentation is erodibility. Anerodibility factor (K) indicates the susceptibility of different soils to the forces of erosion.

A soil survey report includes the K factor for each soil survey area. These K factors areused in the USLE to determine soil loss from an area over time due to splash, sheet, andrill erosion. K factors in Florida range from about 0.10 (the lowest erodibility) to about0.49 (the highest erodibility). K factors are grouped into three general ranges, asfollows:

0.23 and lower – low erodibility;

0.23 to 0.36 – moderate erodibility; and

0.36 and up – high erodibility.

The cohesiveness of soil particles varies within different layers of the same soil, causingvarying degrees of erodibility at different depths. Therefore, the depth of excavationmust be considered in determining soil erodibility on a construction site.

Slope

Slope ranges are recorded in soil surveys, and areas where cuts and fills should beavoided can be identified by studying soil maps. The longer and steeper the slope, thegreater the potential for soil loss due to the increased velocity of surface runoff.


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Shrink-Swell Potential

Certain soils have clays that shrink when dry and swell when wet. In this situation,special foundations are required to allow for this variation. By consulting the soil survey,soils with these problems can be identified and the necessary precautionary steps canbe taken. It should be kept in mind, however, that soil surveys do not always reflect

geologic phenomena in the zone beneath the soil; thus, when shrink-swell conditionsoccur only deep in the soil profile, the soil survey may not be an accurate guide.

Flood Hazard

Although soil survey information does not take the place of hydrologic studies, it doesprovide estimates of where floods are most likely to occur. The hazards of flooding andponding are rated in soil surveys, and flood-prone areas are shown on soil maps.

Soil Reaction (pH)

Soil survey information on the pH of the individual layers of each soil is useful whenplanning to establish vegetation on a construction site.

Wetness

The many types of data available in soil surveys include natural soil drainage, depth toseasonal water table, and suitability for winter grading of various kinds of soils. With thisinformation, engineers can make determinations such as seasonal limitations that shouldbe placed on the use of heavy earth-moving machinery and estimations of potential floodhazards or damage to underground structures due to soil wetness.

Depth to Bedrock

Soil surveys indicate bedrock types and in what areas they will be encountered at adepth of less than 5 to 6 feet (1.75 to 2 meters [m]). This information is very helpful in

determining suitable locations for stormwater management facilities, or the time and costof excavation.

2.3 Soil Surveys

Soil surveys are proven to save time and money, and their use results in improveddesigns, more effective planning, and more accurate preliminary estimates ofconstruction costs. References to soil maps and accompanying supporting data in soilsurveys enable developers to determine the soil conditions in proposed constructionareas.

Knowing the types of soil, the topography, and surface drainage patterns is beneficial inplanning and designing almost any type of land development project and is essential forerosion control planning. In many instances, a major soil-related problem is discoveredafter a site has been selected and construction is either well under way or in some casescompleted. These problems often necessitate delays in construction and ultimatelyincrease the total cost of the project. By consulting a soil survey during the planningprocess prior to construction, compensating designs can be prepared in advance oralternate sites can be selected.


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Soil surveys in Florida are conducted as a joint effort by the NRCS, the AgriculturalExperiment Stations of the University of Florida, and the local Soil and WaterConservation Districts. Soil surveys have been published for most Florida counties.

Additional soils information may be obtained by contacting the local representative ofany of these agencies in your area or at the NRCS website at http://soils.usda.gov.


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CHAPTER 3: REGULATIONS ANDSTATUTORY REQUIREMENTS

3.1 Introduction

3.2 NPDES Stormwater Permit ting Regulations and StatutoryRequirements- 3.2.1 Construction Activities- 3.2.2 Larger Common Plan of Development

Operator

Obtaining CGP Coverage

Key CGP Requirements

Contents of an SWPPP

Narrative Report

Certification Requirement

Contractor Certification Requirement

SWPPP Update Requirements

Posting a Copy of the NOI

Inspections

Retention of Records

Notice of Termination

Dewatering

General Comments

3.3 Construction Stormwater Pollut ion Prevention Plan Template- 3.3.1 Stormwater Pollut ion Prevention Plan

* * * * * * * * * * * * * * * * * * * *

3.1 Introduction

To minimize the adverse impacts of runoff, Florida was the first state in the country torequire stormwater treatment from all new development with the implementation of theState Stormwater Rule in 1982. This technology-based rule includes a goal (theperformance standard) and design criteria for different types of stormwater treatmentBMPs, such as retention or wet detention systems.

Today, a Florida ERP must be obtained from the applicable water management district

or FDEP office before construction begins. ERPs integrate stormwater quantity andquality, as well as wetland protection requirements, into a single permit. They regulateactivities such as dredging and filling in wetlands, the construction of stormwaterfacilities, stormwater treatment systems, the construction of dams or reservoirs, andother activities affecting state waters. Each water management district has an operatingagreement with FDEP about which agency will process ERPs for particular projects,based on the type of land use or activity.


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Specific requirements for stormwater management, including erosion and sedimentcontrol during land disturbance, flood control, and stormwater treatment, are found in thespecific ERP regulations applicable within the appropriate water management district.These requirements include specific design criteria for various types of stormwatertreatment practices. Additional details about these regulations are available athttp://www.dep.state.fl.us/water/wetlands/erp/index.htm or http://flwaterpermits.com.

It is important to note that the permit required under FDEP’s National PollutantDischarge Elimination System (NPDES) Stormwater Program is separate from the ERPrequired under Part IV, Chapter 373, F.S., or any local government’s stormwaterdischarge permit for construction activity.

The FDEP/water management district ERP Program benefits Florida by requiring theimplementation of effective mitigation measures that will minimize stormwater pollutionto Florida's lakes and streams and protect wetlands (see http://www.flwaterpermits.com).

Developers need to identify within which of the five water management districts (see themap below) their project is located to ensure that all permits and environmental issues

are properly addressed within their SWPPP. Also, it will be necessary to contact theappropriate water management district office for specific ERP and dewatering permitrequirements.


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In 2000, the EPA authorized FDEP to implement the NPDES Stormwater Program withinthe state, except for Native American tribal lands. Mandated by the revisions to thefederal Clean Water Act adopted by Congress in 1987, the NPDES Program is anational program for addressing many urban stormwater discharges that may adverselyimpact water quality.

The NPDES Stormwater Program is completely separate from the state’s environmentalresource permitting programs authorized by Part IV, Chapter 373, F.S. The NPDESProgram does not establish additional regulations for construction/design features forretention areas, detention ponds, swales, and other stormwater management systems.The permit required under FDEP’s NPDES Program is also separate from any localgovernment’s stormwater discharge permit for construction activity.

3.2 NPDES Stormwater Permitting Regulations andStatutory Requirements

The sources of stormwater discharges regulated under the NPDES Stormwater Programinclude the following three categories:

Construction activities (addressed in this chapter),

Industrial activities, and

Municipal separate storm sewer systems (MS4s).

3.2.1 Construction Activities

Stormwater runoff from construction activities can have a significant impact on waterquality by contributing sediment and other pollutants to waterbodies. The term“construction activity” means the act or process of developing or improving land that

involves the disturbance of soils and includes clearing, grading, and excavation. Basedon EPA guidance, FDEP has determined that demolition activities also meet thedefinition of construction activities.

The NPDES Stormwater Program regulates construction activities that disturb one ormore acres of land and discharge stormwater to surface waters of the state or into anMS4. (The regulatory definition of an MS4 is “a conveyance or system of conveyanceslike roads with stormwater systems, municipal streets, catch basins, curbs, gutters,ditches, constructed channels, or storm drains.”) If a project is less than one acre, butpart of a larger common plan of development or sale that will ultimately disturb one ormore acres, permit coverage is also required.

3.2.2 Larger Common Plan of Development

separate and distinct construction activities may be taking place at different times and ondifferent schedules under a single plan. The classic example is the construction of asubdivision. If a developer buys a 20-acre parcel, and builds roads and installswater/sewer with the intention of constructing homes or other structures in the future,this is considered a larger common plan or development or sale. If the land is parceledoff or sold, and construction occurs on plots that are less than 1 acre by separate,

A larger common plan of development or sale is a contiguous area where multiple


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independent builders, this activity still is subject to NPDES stormwater permittingrequirements if the smaller plots are included in the original site plan, regardless of thesize of any of the individually owned plots (¼ acre, ½ acre, etc.).

3.2.3 CGP Permit

Responsibili ties of the Operator

The Generic Permit for Stormwater Discharge from Large and Small Construction Activities (CGP) (FDEP Document 62-621.300[4][a], effective May 2003) defines theterm “operator” as follows:

The operator is ultimately responsible for obtaining permit coverage and implementingappropriate pollution prevention techniques to minimize erosion and sedimentation fromstormwater discharges during construction. The operator is the entity with sufficientauthority to ensure compliance with the permit requirements. Typically, the operator isthe owner, developer, or general contractor. Generally, the architect/engineer shouldnot be listed as the operator unless that individual has operational control over theproject and is willing to accept responsibility for compliance with the permit.

For construction projects where the operator changes, the new operator should obtainpermit coverage at least 2 days before assuming control of the project, and the previousoperator should file an NPDES Stormwater Notice of Termination (FDEP Form62-621.300[6]) within 14 days of relinquishing control of the project to a new operator.

The previous operator must meet the conditions to terminate coverage in accordancewith Part VIII of the CGP.

Obtaining CGP Coverage

To obtain NPDES stormwater permit coverage, a regulated construction operator mustcomplete the following steps:

1. Obtain and carefully read the CGP (available online at:http://www.dep.state.fl.us/water/stormwater/npdes/construction3.htm ).

2. Develop a site-specific SWPPP.

3. Complete in its entirety the application or Notice of Intent (NOI) (FDEP

Form 62-621.300[4][b]).

4. Submit the NOI with the appropriate processing fee to the NPDESStormwater Notices Center:4

a. The processing fee is required by Rule 62-4.050(4)(d), F.A.C. (available athttp://www.dep.state.fl.us/legal/Rules/mainrulelist.htm orhttps://www.flrules.org/gateway/RuleNo.asp?ID=62-4.050).

2

4 The fee is subject to change, so check the rule to determine the appropriate fee when applying.

“ . . . the person, firm, contractor, public organization, or other legal entity that owns or

operates the construction activity and that has authority to control those activities at the

project to ensure compliance with the terms and conditions of this permit.”


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A thorough understanding of the plan is essential for proper implementation andmaintenance.

The SWPPP must be developed before an NOI is filed in order to receive CGP coverageand must meet or exceed FDEP requirements. Also, beginning on the first day ofconstruction activities, the SWPPP must be available at the location identified in the NOI.

A SWPPP should consist of a narrative and a site map. The CGP also requires acertification statement to be signed by the operator. The SWPPP must be developedand implemented for each construction site covered by this generic permit and must beprepared in accordance with good engineering practices.

Narrative Report

The narrative report provides general information on the activities that will be completedto ensure minimal environmental damage as a construction project proceeds. It shouldbriefly describe the overall strategy for erosion and sediment control, as well assummarize the aspects of the project that are important for erosion control onsite for theplan reviewer and project superintendent.

The narrative report shall include a site description and, at a minimum, the followinginformation about the site:

Description of the construction activity;

Intended sequence of major soil-disturbing activities;

Total area of the site and total disturbance area;

Description of the soils and an estimate of the size of the drainage area foreach discharge point;

Latitude and longitude of each discharge point and the name of the receivingwater for each discharge point; and

Site map indicating drainage patterns and slopes, areas of soil disturbance,undisturbed areas, locations of BMPs, stabilization areas, surfacewaters/wetlands, and discharge points.

Each plan must include a description of the appropriate controls, BMPs, and measuresthat will be implemented at the construction site. The plan must clearly describe foreach major soil-disturbing activity the appropriate control measures and the timing forimplementing these measures. Control measures include the following:

Erosion and sediment controls such as stabilization practices, structural

practices, and sediment basins;

Permanent stormwater management controls to control pollutants duringconstruction and after construction operations have been completed; and

Controls for other potential pollutants such as waste disposal, offsite vehicletracking, the proper application of fertilizers/herbicides/pesticides, and theproper storage of toxic materials. The permit does not authorize thedischarge of solid materials to surface waters of the state or an MS4.


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Maintenance and inspections of structural (e.g., sediment control) and nonstructural(e.g., erosion control) BMPs are important aspects of the CGP and must be addressedin the SWPPP. The narrative report should briefly describe the procedures that will befollowed to ensure the timely installation, inspection, and maintenance of vegetation,erosion and sediment controls, stormwater management practices, and other protectivemeasures and BMPs so they will remain in good and effective operating condition.

The plan shall also identify and ensure the implementation of appropriate pollutionprevention and treatment measures for nonstormwater components of the discharge.Common nonstormwater discharges include discharges from fire-fighting activities, firehydrant/waterline flushings, water used to spray off loose solids from vehicles, water fordust control, and irrigation drainage.

Certifi cation Requirement

The preparer of the SWPPP or responsible authority must sign and date the followingcertification statement as part of the SWPPP:

“I certify under penalty of law that this document and all attachments wereprepared under my direction or supervision in accordance with a systemdesigned to assure that qualified personnel properly gathered and evaluatedthe information submitted. Based on my inquiry of the person or personswho manage the system, or those persons directly responsible for gatheringthe information, the information submitted is, to the best of my knowledgeand belief, true, accurate, and complete. I am aware that there aresignificant penalties for submitting false information. These include thepossibility of fine and imprisonment for knowing violations.”

Contractor Certification Requirement

All contractors and subcontractors identified in the SWPPP, or those selected at a later

date, must sign and date the following certification statement before conducting land-disturbing activities on the site:

“I certify under penalty of law that I understand, and shall comply with, theterms and conditions of the State of Florida Generic Permit for StormwaterDischarge from Large and Small Construction Activities and this StormwaterPollution Prevention Plan prepared there under.”

SWPPP Update Requirements

The SWPPP is a dynamic document that provides a first appraisal of where to installBMPs on construction sites. Consequently, the SWPPP must be revised within sevencalendar days following an inspection when additions and/or modifications to BMPs are

necessary to correct observed problems. The plan should be revised under thefollowing conditions:

Whenever a change in design, construction, operation, or maintenance at theconstruction site has a significant effect on the discharge of pollutants tosurface waters of the state or to an MS4 system.

Whenever the plan proves to be ineffective in eliminating or significantlyminimizing pollutants from sources or in otherwise achieving the general


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objectives of controlling pollutants in stormwater discharge associated withconstruction activity.

Posting a Copy of the NOI

A copy of the NOI or acknowledgment letter from FDEP confirming coverage must be

posted at the construction site in a prominent place for viewing (such as alongside thebuilding permit).

Inspections

One of the key components of the CGP is the requirement for a qualified inspector toinspect all points of discharge into any surface waters (including wetlands) or an MS4.Disturbed areas, material storage areas, structural controls, and vehicle ingress/egressareas must be inspected and documented at least once every 7 calendar days andwithin 24 hours of the end of a storm event that is ½ inch or greater.

A qualified inspector is defined in the CGP as one of following:

1. Has successfully completed and met all requirements necessary to be fullycertified through the FDEP Stormwater, Erosion, and SedimentationControl Inspector Training Program;

2. Has successfully completed an equivalent formal training program(typically in other states);

3. Is qualified by other training or practical experience in the field ofstormwater pollution prevention and erosion and sedimentation control.

FDEP recommends that inspectors become certified under the Inspector TrainingProgram.

Inspections must be documented and signed by a qualified inspector. If the inspection

reveals that the activity is in compliance with the SWPPP and CGP, the report mustcontain a certification statement indicating that the facility is in compliance. Majorobservations and incidents of noncompliance should also be recorded in the inspectionreport, as well as corrective actions and maintenance. Deficiencies and maintenancemust be corrected and documented within seven calendar days following the inspection.

Retention of Records

The permittee shall retain copies of the SWPPP and all reports required by the CGP,and records of all data used to complete the NOI to be covered by the CGP, for at least3 years from the date that the site is finally stabilized. The permittee shall retain a copyof the SWPPP and all reports, records, and documentation required by the CGP at the

construction site, or an appropriate alternative location as specified in the NOI, from thedate of project initiation to the date of final stabilization.

Notice of Termination

Upon completion of the project and final stabilization, the permittee should submit acompleted NOT to the NPDES Stormwater Notices Center and the MS4, if applicable.The elimination of stormwater discharges associated with construction activity meansthat all disturbed soils at the site have been finally stabilized and temporary erosion and


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sediment control measures have been removed or will be removed at an appropriatetime.

Final stabilization is defined within the CGP as follows: “all soil disturbing activities atthe site have been completed, and . . . a uniform (e.g., evenly distributed, without largebare areas) perennial vegetative cover with a density of at least 70% for all unpaved

areas and areas not covered by permanent structures has been established orequivalent permanent stabilization measures (e.g., geotextiles) have been employed.”

The NOT should be sent to the following address:

NPDES Stormwater Notices CenterFlorida Department of Environmental Protection2600 Blair Stone Road, MS #2510Tallahassee, FL 32399-2400(866) 336–6312 (toll free)

Dewatering

Discharges resulting from ground water dewatering activities at construction sites arenot covered under the CGP. Dewatering activities may require permit coverage underFDEP’s Generic Permit for the Discharge of Produced Ground Water from any Non-contaminated Site Activity under Rule 62-621.300(2), F.A.C. In addition, dewateringmay require an authorization or exemption from the local water management district.

3.3 Construct ion Stormwater Pollution Prevention PlanTemplate

The following template may be used as a general guide for development of a SWPPP forconstruction activities. This template may not contain all applicable requirements for all

construction sites. Please refer to FDEP’s CGP, FDEP Document 62-621.300(4)(a), toverify that you are meeting all permit requirements. Part V of the above referencedgeneric permit specifically lists the requirements of the SWPPP, as follows:

The SWPPP shall be completed prior to the submittal of the NOI to becovered under the CGP.

The SWPPP shall be amended whenever there is a change in design,construction, operation, or maintenance that has a significant effect on thepotential for discharge of pollutants to surface waters of the state or an MS4.The SWPPP also shall be amended if it proves to be ineffective insignificantly reducing pollutants from sources identified in Part V.D.1. of thepermit. The SWPPP also shall be amended to indicate any new contractor

and/or subcontractor that will implement any measure of the SWPPP. Allamendments shall be signed, dated, and kept as attachments to the originalSWPPP.

3.3.1 Stormwater Pollution Prevention Plan

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stormwater erosion and sedimentation control inspector’s manual

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